High sensitivity C-reactive protein levels in Acute Ischemic Stroke and subtypes: A study from a tertiary care center.

BACKGROUND
Stroke is a heterogeneous disease with several risk factors. High sensitivity C-reactive protein (hsCRP) is a marker for cardiovascular and cerebrovascular diseases. Recent studies have shown that high hsCRP level is a risk factor for ischemic stroke. The objective of our study was to investigate the association of high hsCRP (> 3 mg/L) levels with ischemic stroke and its subtypes in Indian patients.


METHODS
We recruited 210 consecutive acute stroke patients and 150 age and sex matched controls. Stroke patients were admitted within 72 hours of onset, at Yashoda Hospital, Hyderabad, India. The study period was from January 2011 to December 2012. All patients underwent tests as per standard protocol for stroke workup. Serum hsCRP level was assessed in all stroke patients and controls on the day of admission.


RESULTS
The mean hsCRP was significantly higher in stroke patients (3.8 ± 2.5) than controls (1.8 ± 1.5) (P < 0.001). High hsCRP had higher frequency in stroke patients 130 (61.9%) compared to controls 10 (6.6%), P < 0.001. High hsCRP level was more prevalent in the stroke subtypes of cardioembolic stroke (83.3%) and large artery atherosclerosis (72%). High hsCRP level was significantly associated with hypercholesterolemia (P = 0.001), age (P = 0.01), and mortality (0.04). After adjustment of regression analysis it was observed that high level hsCRP is independently associated with acute ischemic stroke (Odds 4.5; 95% CI: 2.5-12.2); especially the stroke subtypes of cardioembolic stroke, (odds ratio 3.4, 95% CI: 1.9-10.5) and large artery atherosclerosis (odds ratio 2.1, 95% CI: 1.5-3.8).


CONCLUSION
High hsCRP level is strongly associated with and an independent predictor of acute ischemic stroke. The association was found in all ischemic stroke subtypes.


icturition, a
d asymptomatic subjects with evidence of infection on investigations such as leucocytosis on peripheral smear, pus cells in urine, infiltrates on chest radiograph, since they may cause elevation of hsCRP, were excluded.Patients with a history of prior inflammatory diseases, like rheumatoid arthritis and systemic lupus erythematosus (SLE), and those on steroids or immunomodulatory drugs were also excluded.Stroke was defined according to the World Health Organization as "rapidly developing clinical signs of focal/global disturbance of cerebral function, with symptoms lasting 24 hours or longer or leading to death, with no apparent cause other than of vascular origin". 13Cerebral infarction was diagnosed on the basis of history, neurological examination, and neuroimaging (CT or brain MRI).All subtypes of ischemic stroke were included.150 age and sex matched control subjects were recruited from the same hospital.Controls were healthy s

jects chosen from pati
nts with no present or past history of stroke, transient ischemic attack (TIA), or cardiac disease.Yashoda Hospital is a major referral centre in Andhra Pradesh state.The study period was two years, from January 2011 to December 2012.This study was approved by the Institutional Ethical Committee.


Stroke subtypes assessment

All stroke patients underwent brain imaging by computerised tomography (CT) scan, and when clinically appropriate magnetic resonance imaging (MRI) and intracranial magnetic resonance angiography (MRA) of the brain.Cardiac evaluation with transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE), and non-invasive vascular imaging (extracranial duplex Doppler) were done in all patients.Additional tests were performed when required.The stroke specialist reviewed the data and subclassified the strokes as extracranial large artery atherosclerosis, intracranial large artery atherosclerosis, cardioembolic, small vessel disease (lacunar), stroke of other determined etiology, and stroke of undetermined etiology. 14tandardized techniques were adapted from the behavioural risk factor surveillance system. 15Data were collected through face-to-face interviews of patients, and physical and neurological examination by a stroke specialist.When the subjects were unable to provide answers, their close relations who were knowledgeable about the subject's history were interviewed.All stroke patients and control subjects underwent blood tests which included fasting blood sugar, lipid profile, homocysteine levels, and other biochemical and haematological tests.Collagen diseases profile and tests for prothrombotic state were done, if stroke subtype was not clear.Risk factor definitions were the same as in our previous publication. 16stimation of hsCRP Levels of hsCRP were estimated by VITROS 5.1 chemistry system and VITROS 5600 integrated system to quantitatively measure CRP in human serum or plasma.As per the normative data from VITROS 5600 system manual and current literature, the cardiovascular risk was determined as low risk with hsCRP levels < 1.0 mg/L, medium risk if 1.0-3.0mg/L, high risk when > 3.0 mg/L. 12For our study we considered hsCRP level of ≥ 3 mg/L as high risk and ≤ 3 mg/L as low risk. 12


Statistical analysis

Statistical analysis was done using the Statistical Package for Social Sciences (SPSS 16.0, SPSS Production Facility, Chicago, Illinois, USA).Continuous variables were presented in titre of mean ± SD.Categorical variables were expressed as proportions, and chisquare test was used to study the association in proportions.All tests were two sided and p values < 0.05 were considered statistically significant.We performed multiple logistic regression analysis for stroke subtypes and high hsCRP.


Results

We recruited 210 acute ischemic stroke patients and 150 age and sex matched control subjects for the period of two years.On comparison of hsCRP levels and other vascular risk factors among stroke patients and control subjects it was found that a significantly higher proportion of stroke patients had hypertension, diabetes, and high hsCRP levels (Table 1 Out of 210 stroke patients, high hsCRP levels were detected in 130 (61.9%).On comparison between high and low hsCRP groups it was found that hypercholesterolemia, older age, and mortality were significantly associated with high hsCRP levels (Table 3).

After adjustment of multiple logistic regression analysis, high hsCRP was independently associated with acute ischemic stroke (OR 4.5; 95% CI 2.5-12.2) overall, and in stroke subtypes of cardioembolic stroke (OR 3.4; 95% CI 1.1-10.5)and large artery atherosclerosis (OR 2.1; 95% CI 1.1-3.8)(Table 4).


Discussion

In this present prospective study, more than three fifths of Indian patients with acute ischemic stroke had high hsCRP (> 3 mg/l) levels.Other studies have shown varying prevalence.Rajput et al. had found that among st

ke patients from Paki
tan, 132 (88%) had elevated CRP (CRP > 10 mg/L). 17Moreover, in a study by Di Napoli et al. from Italy, 95 patients (74.2%) with acute ischemic stroke had high CRP levels (> 0.5 mg/dl) at admission. 18Muir et al. had detected elevated CRP (> 10 mg/L) levels in 96 out of the228 (42.1%) patients admitted with acute ischemic stroke in the UK. 19On the other hand, only 22% of stroke patients and 14% of myocardial infarction patients had high CRP (> 7 mg/l) levels in a study from Netherlands. 20This

ariance
ay be explained partly by the different definitions of high CRP in various studies.The hsCRP levels are now becoming universally standardised and most centres accept a value above 3 mg/dl as high. 12RP has evolved from being an association to a risk factor for vascular pathology of heart and brain.Zacho et al., in his population based study, found a high frequency of ischemic heart disease (32%) and ischemic stroke (25%) among patients with high levels of CRP in Denmark. 21Ridker et al. from the US, showed high CRP to be a predictor of risk for future myocardial infarction and stroke in healthy men. 22Among the Japanese population Arima et al. showed a significant association between high hsCRP and future risk of coronary artery disease. 23Moreover, CRP has also been associated with poorer outcomes in cardio and cerebrovascular diseases.In recent studies evaluating various biomarkers, including atrial and brain natriuretic peptides, CRP, and homocysteine, in outcome of stable cardiovascular diseases showed that CRP was associated with an increased risk of congestive heart failure. 24Thus there is increasing evidence that hsCRP is a risk as well as prognostic factor for ischemic stroke and coronary events. 10,20,25,26troke subtypes In this study, high hsCRP levels were associated with all stroke subtypes.Prevalence of high hsCRP was maximum in cardioembolic stroke (83.3%) followed by large artery atherosclerosis (both intracranial and extracranial) (72%) and small artery disease (50%).


Large artery atherosclerosis

Among our patients with large artery atherosclerosis, high hsCRP levels were found in 72%.This is similar to reports by Huang et al. (63.9% in large artery atherosclerosis) 12 and Rajeshwar et al. 27 who observed high CRP in both intracranial (48.7%) and extracranial large artery atherosclerosis (54.9%). 27In contrast, studies from the West seem to have a much lower percentage of high hsCRP levels.Den Hertog et al. 20 and Dewan et al. 28 noted that 15% and 14.9% of patients with large artery atherosclerosis, respectively, had high CRP levels.After adjustment using multiple logistic regression, high hsCRP was an independent predictor in this group (odds ratio: 2.1, 95% CI: 1.3-3.8)and these findings were advocated by Ladenvall et al. 29


Cardioembolic stroke

We found 83.3% of our cardioembolic patients had high hsCRP levels.The other study from India by Rajeshwar et al. also reported an increased prevalence of high hsCRP levels in 58.3% of patients with cardioembolic stroke. 27Lower prevalence was noted in other regions of the world; 13.8% in Nepalese,

d 24% in Dutch populations. 2
,28Increased prevalence of high hsCRP levels in cardioembolic stroke seems to be a unique feature of the Indian population.The underlying cardiac disease in the high hsCRP group was varied and included ascending aorta stenosis (4 patients), congestive heart failure (3 patients), mitral stenosis (4 patients), atrial fibrillation (6 patients), and rheumatic heart disease (3 patients).Our study demonstrated that high hsCRP was significantly associated with cardioembolic stroke (Odds ratio: 3.4 95% CI: 1.9-10.5)and is an independent predicator of cardioembolic stroke.


Small vessel disease

Compared to large artery atherosclerosis and cardioembolic stroke, the prevalence of high hsCRP levels was lower among stroke patients due to small vessel di

ase.The 50% prevalenc
found in our study is similar to that detected by others.Muir et al. observed that (21/96) 21.8% of acute ischemic patients with small vessel disease had elevated CRP > 10 mg/L and 29.8% of lacunar patients from Nepal had high CRP levels. 19,28Den Hertog reported that 13% of patients with small vessel disease had high hsCRP. 20ajeshwar et al. observed a 12.6% prevalence of high hsCRP levels. 27The association of high hsCRP with different stroke subtypes in different populations may be secondary to unknown interactions with genetic and environmental pathogenetic factors.


Stroke of other determined etiology

In this study, patients with stroke of other determined etiology had 40% prevalence of high hsCRP levels (3 patients had hyperhomocysteinemia, 2 had deficiency of protein C, and 1 patient antithrombin III deficiency), which is comparable to that noted by Rajeshwar et al. (25.9%). 27


Stroke

f undetermined etiolo
y

In our study we noted that 49% of patients with stroke of undetermined etiology had high hsCRP levels.These findings were advocated by Rajeshwar et al. (36.7%). 27en Hertog also confirmed these findings and noted 44% with high CRP (> 7 mg/dl) levels. 20The literature is meagre on this stroke subtype, and multiple logistic regression showed that high hsCRP is not an independent Atherogenicity of CRP CRP, an acute-phase protein synthesised by hepatocytes, is released in the blood stream in response to inflammation and tissue damage. 30,31CRP stimulates the endothelial cells to produce various adhesion molecules, such as intracellular adhesion molecule-1, vascular cell adhesion molecule-1, and E-selectin. 32,33These molecules allow migration of mononuclea

cells and T lymphocytes into the ves
el wall and play a key role in the formation of atherosclerotic plaque. 34,35CRP also helps in releasing of superoxide anion and stimulation of tissue factor activity. 368][39] Finally, CRP may increase the chance of endothelial cell lysis, and plaque erosion, and can precipitate acu

ischemic stroke or coronary syn
rome.All these, thus, predispose to atherosclerosis in cerebral and cardiac circulation.


Association between gender and hsCRP

In our study, the proportion of men with high hsCRP levels was significantly higher (95; 73%) compared to low hsCRP (38; 47.5%); and recent studies have found similar findings. 41Devaraj et al. 42 and Wakugawa et al. 9 found that raised hsCRP level was an

ndependent risk factor f
r future ischemic

troke only in men and not in w
men.Endogenous estrogen has been shown to protect the development of atherosclerosis, and has an anti-inflammatory effect in women. 43,44However, Muir et al. did not find any association between gender and elevated CRP (> 10 mg/L) levels in acute ischemic stroke patients. 19Recent studies have demonstrated a fivefold increase in the risk of any vascular event in women with the highest CRP levels. 7,23Thus, elevated CRP level may cause more damage in women.


Association between age and hsCRP

We demonstrated that high plasma hsCRP level was significantly associated with older age in our patients; similar to the British population. 19Rost et al. found elevated CRP level to be a significant predictor of future risk of ischemic cerebrovascular accident in the elderly. 45Large prospective studies in apparently healthy subjects have confirmed the prognostic relevance of CRP in the elderly. 46,47


Mortality in the hospital

In the present study, 9 (4.2%) patients died in the hospital due to the diseas

progression.The Mortality rate was si
nificantly higher in our patients with high hsCRP.Studies in Nepal, Norway, and China had similar findings. 12,27,48Furthermore, the impact of CRP on mortality seems to be long-term.A recent study showed that elevated CRP levels in young patients with ischemic stroke were associated with an increased risk of mortality, even 12 years after the CRP measurements. 49


Conclusion

In conclusion, this study demonstrated that high levels of hsCRP are prevalent in all ischemic stroke subtypes, and are independently associated with large artery atherosclerosis and cardioembolic stroke.In stroke subtypes, high hsCRP levels were associated with a 3fold increase in risk of developing cardioembolic stroke and a 2-fold raise in risk of large artery atherosclerosis.Hence, in these subtypes high hsCRP

y be a marker to initiate primary
reventive strategies.In the Jupiter trial, statins decreased the risk of myocardial infarction and ischemic stroke in patients with high hsCRP levels. 50hus, high hsCRP levels may be a marker for starting therapy with statins for both primary and secondary prevention.Future large scale studies are required to explore these findings.

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Chaudhuri et al. http://ijnl.tums.ac.ir 4